During manufacturing of a semiconductor device, the device is usually processed at many work stations or processing machines. The transporting or conveying of a partially finished device, or a work-in-process (WIP) part, is an important aspect in the total manufacturing process. The conveying of semiconductor wafers is especially important in the manufacturing of integrated circuit (IC) chips due to the delicate nature of the chips. Furthermore, in fabricating an IC product, a multiplicity of fabrication steps, i.e. as many as several hundred, is usually required to complete the fabrication process. A semiconductor wafer or IC chips must be stored or transported between various process stations in order to perform various fabrication processes.
Automated Material Handling Systems (AMHS) have been widely used in semiconductor fabrication facilities (“FABs”) to automatically handle and transport groups or lots of wafers between various processing machines (“tools”) used in chip manufacturing. Multiple wafers are typically stored and transported together in wafer carriers by the AMHS between load ports of different wafer processing or other tools during the semiconductor fabrication process. The load port is used to handle not only semiconductor wafers but also different types of substrates to be processed such as liquid crystal display glass substrates and photomask glass substrates.
The AMHS in a semiconductor FAB includes numerous types of automated and manual vehicles for moving and transporting the wafer carriers throughout the FAB during the manufacturing process. This can include for example automatic guided vehicles (AGVs), personal guided vehicles (PGVs), rail guided vehicles (RGVs), overhead shuttles (OHSs), and overhead hoist transports (OHTs). Of the foregoing AMHS wafer transport mechanisms, OHTs are commonly used to transport wafer carriers, from the load port of one tool to the load port of the next tool in the processing sequence. A wafer carrier transported by an OHT transfer system typically has a door during the transfer process for production quality control, e.g. to seal the wafer carrier against entry of external contaminants to keep wafers inside the wafer carrier clean, and/or to protect the wafers from falling off the wafer carrier.
A conventional load port is used to load and unload a wafer carrier in a FAB. But it needs a human being to manually open the door of the wafer carrier and put the wafer carrier into the load port, which causes a bottle neck of work efficiency in the FAB. As such, an apparatus and method for handling wafer carrier doors to solve the above mentioned problems is desired.